Glomerular filtration evaluation

Histopathological evidence of renal damage has been observed in lead-exposed workers. Renal ultrastructure and function were examined in five men with heavy occupational exposure to lead (Cramer et al. 1974). In addition, renal function was evaluated in two men from whom renal biopsies were not obtained. PbB levels ranged from 71 to 138 pg/dL. Renal function tests were normal in all except for a reduced glomerular filtration rate in one worker. Two subjects with relatively short exposure to lead (6 weeks and 8 months) and PbB levels of 89-129 pg/dL had intranuclear inclusions in the proximal tubules. Renal biopsies from workers with longer periods of lead exposure (4-20 years, PbB levels of 71-138 pg/dL) had diffuse interstitial or peritubular fibrosis. Glomeruli were normal in all subjects. 

Elevated BUN and serum creatinine It is not unusual for serum creatinine and BUN levels to be elevated during cyclosporine therapy. These elevations in renal transplant patients do not necessarily indicate rejection, and each patient must be fully evaluated before dosage adjustment is indicated. These increases reflect a reduction in the glomerular filtration rate. Impaired renal function at any time requires close monitoring, and frequent dosage adjustments may be indicated. The frequency and severity of serum creatinine elevations increase with dose and duration of cyclosporine therapy. These elevations are likely to become more pronounced without dose reduction or discontinuation. 

After the equilibration period, clearance periods of 20 min are used. Urine samples are collected and perfusate is obtained at midpoint of the clearance period for the evaluation of overall kidney function. For determination of glomerular filtration rate (GFR) and fluid transport, 3H-labelled polyethylene glycol is added to a modified Krebs-Henseleit bicarbonate buffer. Electrolytes are determined in urine by standard flame photometry. Fractional excretions of water, electrolytes and test compounds are calculated. 

Renal function in 14 children born to women with transplants treated throughout pregnancy with a ciclosporin-based regimen has been extensively investigated at a mean of 2.6 years after delivery (205). No renal function abnormahties were found. In particular, glomerular filtration rate was within the reference range. Renal function was found to be normal in 22 children evaluated after a mean of 39 months after birth (206), and no adverse effects on the immune function were identified in the few infants examined in this respect (203). 

The effect of COX-2 specific inhihitors on renal function, including sodium excretion, has heen assessed in prostaglandin dependent patients. Catella-Lawson et al. [26] enrolled 36 healthy elderly patients for her study, which evaluated not only sodium excretion and glomerular filtration rates, but also changes in body... 

The prevalence of polyuria among unselected lithium-treated patients has been difficult to ascertain [11]. Polyuria, as defined by a 24-hour urine output exceeding 3 L, varies considerably among patients on chronic Uthium therapy [67-80]. In a review of a total of 841 unselected patients evaluated for 24-hour urine volume, we found that 160 (or 19%) had polyuria as defined by fhese criferia [11]. If was found fhat 85% of hthium treated patients have a normal glomerular filtration rate and that the remaining 15% have only mild reductions in renal function [11]. After fluid deprivation of approximately 24-hours duration, normal individuals should be able to raise urinary osmolahty above 800 mOsm/kg HjO. In a survey of a total of 1,105 lithium-treated patients [69-74], we found that at least 602 (or 54%) had a subnormal concentrating ability defined by this criterion [11]. 

Different methods of kidney imaging have shown that Balkan nephropathy patients with chronic renal failure have symmetrically shrunken kidneys with smooth surface and no calcifications [90]. The time at which the shrinking occurs remains to be determined. While some authors suggest that the size of the kidneys remains normal in patients in the latent phase of the disease and with normal renal function, others report cases of shrunken kidneys in patients in an early phase with normal glomerular filtration rate, and it was even proposed that the disease was characterized with primarily small kidneys [98, 110, 112]. As ultrasound became a standard imaging method in the evaluation of kidney dimensions, several recent studies that used this method showed diminished kidney length and cortex width in members of Balkan nephropathy families with normal kidney function [113, 114]. Besides,... 

Creatinine is the end product of creatine catabolism. It is found in muscle tissue, blood, and urine as it is formed from the breakdown of muscle creatinine, and is proportional to the muscle mass. It results from the irreversible nonenzymatic dehydration and loss of phosphate from phosphocreatine, as shown in Fig. 2. Creatinine concentrations are very useful indices for evaluating glomerular filtration rate and, in general, are an important clinical marker of renal function. 

Orlando R, Roreani M, Padrini R, Palatini P. Evaluation of measured and calculated creatinine clearances as glomerular filtration markers in different stages of liver cirrhosis. Clin Nephrol 1999 51 341-347. 

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